Provisioning of young after weaning or fledging is a highly variable phenomenon. Among cooperative breeders, such as marmosets and tamarins, both parents and natal adults may provision immatures. Experiments designed to measure the effects of food familiarity on food-transfer interactions were conducted on zoo-living golden lion tamarin, Leontopithecus rosalia, families to test one proposed benefit of provisioning to recipient young — that immature callitrichids learn food preferences through exposure to food items obtained from older group members. Adults transferred to immatures foods that were known to adults, but novel to immatures, and foods that were novel to all more frequently than foods that were familiar to both adults and immatures. Results suggest that adults alter their behavior such that learning by immatures is fostered. Immatures also were less likely to reject new foods acquired from other group members, compared with those obtained independently, suggesting the possibility that immatures attend to food transfer to facilitate incorporation of new foods into the diet. In contrast, anecdotal accounts of wild marmoset and tamarin food transfer have indicated that infants receive from adults foods that primarily are high in lipids and/or protein, as expected if provisioning acts to supplement nutrition. These apparently contradictory findings may reflect the differing effects of the captive and wild environment on food-transfer behavior or may point to a dual function of provisioning dependent on age of the recipient.